Despite advances in the treatment of patients with shock and head injuries, the combination of traumatic brain injury and hemorrhagic shock is the leading cause of death and disability in children and adults in their most productive years. An estimated 1.6 million head injuries occur every year in the United States. The economic consequence of these grave injuries in terms of both lost productivity and the cost of medical care is estimated at over 100 billion dollars annually in the United States alone. While the last two decades of research has resulted in a greater understanding of the physiologic events leading to secondary neuronal injury following polytrauma, therapeutic advances are desperately needed. The goal of this Phase 1 SBIR application is to develop and evaluate a novel device, the intrathoracic pressure regulator (ITPR), intended to decrease the detrimental effects of secondary brain injury following traumatic head injury and shock. This SBIR application is based upon the discovery by the applicants that decreasing intrathoracic pressures with the ITPR lowers intracranial pressures while concurrently increasing cardiac output and blood pressure. The new device is inserted into a standard respiratory circuit between the patient and a means to ventilate the patient. It functions by decreasing a patient's intrathoracic pressure. The decrease in intrathoracic pressure creates a vacuum within the thorax relative to the rest of the body, thereby enhancing blood return to the heart while simultaneously decreasing intracranial pressures. This phase 1 investigation proposes to a) establish proof of concept that a novel intrathoracic pressure regulator valve is a useful and effective resuscitation technology in animals with elevated intracranial pressures and hemorrhagic shock, and b) add a custom variable rate vacuum regulator and prototype a display monitor for the intrathoracic pressure regulator (ITPR) system. If successful, Phase 2 studies will address the potential clinical efficacy of the ITPR in patients with polytrauma including traumatic brain injury. Traumatic brain injury affects hundreds of thousands of Americans each year, accounting for as many as 60,000 deaths and an estimated 70,000 to 90,000 patients with permanent neurologic disabilities. Use of the ITPR is expected to significantly improve patient outcomes, based upon the increase in blood flow to the heart and brain and the lowering of intracranial pressures observed in animal studies. If a significant clinical benefit is demonstrated, the ITPR could become a standard piece of equipment and treatment for patients with hemorrhagic shock and traumatic brain injury. [unreadable] [unreadable]